Grey area in Embedded WMLES on a transonic nacelle-aircraft configuration

A scale resolving hybrid RANS-LES technique is applied to an aircraft-nacelle configuration under transonic flow conditions using the unstructured, compressible TAU solver. Therefore, a wall modelled LES methodology is locally applied to the nacelle lower surface in order to examine shock induced separation. In this context a synthetic turbulence generator (STG) is used to shorten the adaption region at the RANS-LES interface. Prior to the actual examinations, fundamental features of the simulation technique are validated by simulations of decaying isotropic turbulence as well as a flat plate flow. For the aircraft-nacelle configuration at a Reynolds number of 3.3 million a sophisticated mesh with 420 million points was designed which refines 32 % of the outer casing surface of the nacelle. The results show a development of a well resolved turbulent boundary layer with a broad spectrum of turbulent scales which demonstrates the applicability of the mesh and method for aircraft configurations. Furthermore, the necessity of a low dissipation low dispersion scheme is demonstrated. However, the distinct adaption region downstream of the STG limits the employment of the method in case of shock buffet for the given flow conditions

Ecosystem services in smallholder coffee farming systems: a case study in Uganda using chemical soil indicators

Farmers in coffee producing countries may not be aware of the economic, social and ecological benefits available through organic agriculture. At a local, regional and global scale, smallholder coffee farmers can discover that organic production methods are linked to provisioning, regulating, cultural and supporting ecosystem services. It is assumed that organic agriculture has a significant influence on soil parameters, and by association, on ecosystem services. Differences between farming systems in soil chemical properties reveal advantages for coffee farmers and shows the ecosystem services derived through organic agriculture at a local level. Benefits discovered in organic coffee systems are higher inputs of organic matter, higher biodiversity of soil microorganisms, less soil erosion, and the potential for higher aggregate stability and superior nutrient circulation

Application of a Synthetic Turbulence Generator in Aircraft and Turbomachinery Aerodynamics

Methods for generating synthetic turbulent fluctuations in numerical flow simulations have gained increasing attention over the past years. Applications of synthetic turbulence generators (STG) range from initializing whole turbulent flow fields to posing turbulent boundary conditions in LES simulations to generating acoustic sources for the computation of sound propagation. In the DLR project ADaMant one specific method, the NTS-STG, has been applied in two rather different fields with different underlying mechanisms in mind: on the one hand, in order to allow for local wall-modelled LES (WM-LES) on the surface of e.g. an aircraft wing or engine nacelle, the STG is applied inside the fully turbulent boundary layer to ensure quick transition from RANS to WMLES. On the other hand, the STG is used to provide realistic ambient turbulence levels in the freestream of turbomachine components, in order to simulate transitional (laminar/turbulent) flow. Both types of applications of the NTS-STG are put in a common context, highlighting their specific requirements on the STG as well as current deficiencies and potential improvements

Lobar Dementia due to Extreme Widening of Virchow-Robin Spaces in One Hemisphere

Widened perivascular spaces known as Virchow-Robin spaces (VRS) are often seen on MRI and are usually incidental findings. It is unclear if enlarged VRS can be associated with neurological deficits. In this report, we describe a case of lobar dementia associated with unusual VRS widening in one cerebral hemisphere. A 77-year-old woman, seen at a memory clinic, presented with progressive cognitive decline, left hemianopsia, and mild pyramidal signs on the left side. On MRI, unusually wide VRS were visible, predominantly in the right centrum semiovale and the right temporo-occipital white matter. The clinical syndrome was consistent with the extent and location of the abnormally dilated VRS. The high MR signal in white matter bridges between the VRS suggested parenchymal damage, possibly representing gliotic white matter. No evidence for another etiology was found on cerebral MRI and rCBF SPECT. As a conclusion, enlarged VRS in one cerebral hemisphere may be associated with cognitive change and neurological deficits

Modelling Social-Technical Attacks with Timed Automata

Attacks on a system often exploit vulnerabilities that arise from human behaviour or other human activity. Attacks of this type, so-called socio-technical attacks, cover everything from social engineering to insider attacks, and they can have a devastating impact on an unprepared organisation. In this paper we develop an approach towards modelling socio-technical systems in general and socio-technical attacks in particular, using timed automata and illustrate its application by a complex case study. Thanks to automated model checking and automata theory, we can automatically generate possible attacks in our model and perform analysis and simulation of both model and attack, revealing details about the specific interaction between attacker and victim. Using timed automata also allows for intuitive modelling of systems, in which quantities like time and cost can be easily added and analysed

Towards LES-RANS/LES coupling for simulation of a wind turbine rotor in a nocturnal atmospheric condition

A segregated approach with either synthetically generated velocity fluctuations or a precursor Large-Eddy Simulation (LES) of the atmospheric boundary layer (ABL) and a subsequent hybrid RANS/LES (HRLS) of the resolved rotor is presented in this paper. At first the approach is validated with synthetically generated velocity fluctuations that resemble neutrally stratified conditions. Subsequently the same turbine is artificially exposed to a stably stratified atmospheric inflow (nocturnal boundary layer) with a comparable mean velocity but different shear and veer characteristics. The HRLS simulations with the neutrally stratified and stably stratified inflow are compared to LESs with an implemented actuator disc (AD) model. The presented work is a first important step towards a digital twin for research wind parks

Exploring the evolution of the proteins of the plant nuclear envelope

In this study, we explore the plasticity during evolution of proteins of the higher plant nuclear envelope (NE) from the most ancestral plant species to advanced angiosperms. The higher plant NE contains a functional Linker of Nucleoskeleton and Cytoskeleton (LINC) complex based on conserved Sad1-Unc84 (SUN) domain proteins and plant specific Klarsicht/Anc1/Syne homology (KASH) domain proteins. Recent evidence suggests the presence of a plant lamina underneath the inner membrane and various coiled-coil proteins have been hypothesised to be associated with it including Crowded Nuclei (CRWN; also termed LINC and NMCP), Nuclear Envelope Associated Protein (NEAP) protein families as well as the CRWN binding protein KAKU4. SUN domain proteins appear throughout with a key role for mid-SUN proteins suggested. Evolution of KASH domain proteins has resulted in increasing complexity, with some appearing in all species considered, while other KASH proteins are progressively gained during evolution. Failure to identify CRWN homologs in unicellular organisms included in the study and their presence in plants leads us to speculate that convergent evolution may have occurred in the formation of the lamina with each kingdom having new proteins such as the Lamin B receptor (LBR) and Lamin-Emerin-Man1 (LEM) domain proteins (animals) or NEAPs and KAKU4 (plants). Our data support a model in which increasing complexity at the nuclear envelope occurred through the plant lineage and suggest a key role for mid-SUN proteins as an early and essential component of the nuclear envelope